8371718: (sc) Channels.new{Input,Output}Stream can allocate unbounded memory for a socket channel

Reviewed-by: alanb

Author: Brian Burkhalter

src/java.base/share/classes/sun/nio/ch/ChannelInputStream.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2024, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2025, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -109,6 +109,7 @@ public synchronized int read(byte[] bs, int off, int len)
         if (len == 0)
             return 0;
 
+        len = Math.min(len, Streams.MAX_BUFFER_SIZE);
         ByteBuffer bb = ((this.bs == bs)
                          ? this.bb
                          : ByteBuffer.wrap(bs));

src/java.base/share/classes/sun/nio/ch/ChannelOutputStream.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2021, 2025, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -64,10 +64,15 @@ WritableByteChannel channel() {
      * If the channel is selectable then it must be configured blocking.
      */
     private void writeFully(ByteBuffer bb) throws IOException {
-        while (bb.remaining() > 0) {
+        int pos = bb.position();
+        int rem = bb.limit() - pos;
+        while (rem > 0) {
+            bb.limit(pos + Math.min(Streams.MAX_BUFFER_SIZE, rem));
             int n = ch.write(bb);
             if (n <= 0)
-                throw new RuntimeException("no bytes written");
+                throw new IOException("Write failed");
+            pos += n;
+            rem -= n;
         }
     }
 

src/java.base/share/classes/sun/nio/ch/NioSocketImpl.java

@@ -78,10 +78,6 @@
 public final class NioSocketImpl extends SocketImpl implements PlatformSocketImpl {
     private static final NativeDispatcher nd = new SocketDispatcher();
 
-    // The maximum number of bytes to read/write per syscall to avoid needing
-    // a huge buffer from the temporary buffer cache
-    private static final int MAX_BUFFER_SIZE = 128 * 1024;
-
     // true if this is a SocketImpl for a ServerSocket
     private final boolean server;
 
@@ -355,8 +351,8 @@ private int read(byte[] b, int off, int len) throws IOException {
                 // emulate legacy behavior to return -1, even if socket is closed
                 if (readEOF)
                     return -1;
-                // read up to MAX_BUFFER_SIZE bytes
-                int size = Math.min(len, MAX_BUFFER_SIZE);
+                // read up to Streams.MAX_BUFFER_SIZE bytes
+                int size = Math.min(len, Streams.MAX_BUFFER_SIZE);
                 int n = implRead(b, off, size, remainingNanos);
                 if (n == -1)
                     readEOF = true;
@@ -453,8 +449,8 @@ private void write(byte[] b, int off, int len) throws IOException {
                 int pos = off;
                 int end = off + len;
                 while (pos < end) {
-                    // write up to MAX_BUFFER_SIZE bytes
-                    int size = Math.min((end - pos), MAX_BUFFER_SIZE);
+                    // write up to Streams.MAX_BUFFER_SIZE bytes
+                    int size = Math.min((end - pos), Streams.MAX_BUFFER_SIZE);
                     int n = implWrite(b, pos, size);
                     pos += n;
                 }

src/java.base/share/classes/sun/nio/ch/SocketChannelImpl.java

@@ -1373,6 +1373,7 @@ int blockingRead(byte[] b, int off, int len, long nanos) throws IOException {
             // nothing to do
             return 0;
         }
+        len = Math.min(len, Streams.MAX_BUFFER_SIZE);
 
         readLock.lock();
         try {
@@ -1469,7 +1470,7 @@ void blockingWriteFully(byte[] b, int off, int len) throws IOException {
                 beginWrite(true);
                 configureSocketNonBlockingIfVirtualThread();
                 while (pos < end && isOpen()) {
-                    int size = end - pos;
+                    int size = Math.min(end - pos, Streams.MAX_BUFFER_SIZE);
                     int n = tryWrite(b, pos, size);
                     while (IOStatus.okayToRetry(n) && isOpen()) {
                         park(Net.POLLOUT);

src/java.base/share/classes/sun/nio/ch/Streams.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2021, 2025, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -33,6 +33,10 @@
  * Factory methods for input/output streams based on channels.
  */
 public class Streams {
+    // The maximum number of bytes to read/write per syscall to avoid needing
+    // a huge buffer from the temporary buffer cache
+    static final int MAX_BUFFER_SIZE = 128 * 1024;
+
     private Streams() { }
 
     /**

test/jdk/java/nio/channels/Channels/SocketChannelStreams.java

@@ -22,10 +22,10 @@
  */
 
 /* @test
- * @bug 8279339
- * @run testng SocketChannelStreams
+ * @bug 8279339 8371718
  * @summary Exercise InputStream/OutputStream returned by Channels.newXXXStream
  *    when channel is a SocketChannel
+ * @run testng SocketChannelStreams
  */
 
 import java.io.Closeable;
@@ -35,6 +35,8 @@
 import java.net.InetAddress;
 import java.net.InetSocketAddress;
 import java.net.Socket;
+import java.nio.ByteBuffer;
+import java.nio.channels.ByteChannel;
 import java.nio.channels.Channels;
 import java.nio.channels.IllegalBlockingModeException;
 import java.nio.channels.ServerSocketChannel;
@@ -51,6 +53,9 @@
 
 @Test
 public class SocketChannelStreams {
+    // Maximum size of internal temporary buffer
+    private static final int MAX_BUFFER_SIZE = 128*1024;
+
     private ScheduledExecutorService executor;
 
     @BeforeClass()
@@ -379,6 +384,25 @@ public void testIndexOutOfBoundsException() throws Exception {
         });
     }
 
+    /**
+     * Test that internal buffers have at most MAX_BUFFER_SIZE bytes remaining.
+     */
+    public void testReadLimit() throws IOException {
+        InputStream in = Channels.newInputStream(new TestChannel());
+        byte[] b = new byte[3*MAX_BUFFER_SIZE];
+        int n = in.read(b, 0, b.length);
+        assertEquals(n, MAX_BUFFER_SIZE);
+    }
+
+    /**
+     * Test that internal buffers have at most MAX_BUFFER_SIZE bytes remaining.
+     */
+    public void testWriteLimit() throws IOException {
+        OutputStream out = Channels.newOutputStream(new TestChannel());
+        byte[] b = new byte[3*MAX_BUFFER_SIZE];
+        out.write(b, 0, b.length);
+    }
+
     // -- test infrastructure --
 
     private interface ThrowingTask {
@@ -477,4 +501,40 @@ private Future<?> scheduleInterrupt(Thread t, long delay) {
     private Future<?> schedule(Runnable task, long delay) {
         return executor.schedule(task, delay, TimeUnit.MILLISECONDS);
     }
+
+    /**
+     * ByteChannel that throws if more than 128k bytes remain
+     * in the buffer supplied for reading or writing.
+     */
+    private static class TestChannel implements ByteChannel {
+        @Override
+        public int read(ByteBuffer bb) throws IOException {
+            int rem = bb.remaining();
+            if (rem > MAX_BUFFER_SIZE) {
+                throw new IOException("too big");
+            }
+            bb.position(bb.limit());
+            return rem;
+        }
+
+        @Override
+        public int write(ByteBuffer bb) throws IOException {
+            int rem = bb.remaining();
+            if (rem > MAX_BUFFER_SIZE) {
+                throw new IOException("too big");
+            }
+            bb.position(bb.limit());
+            return rem;
+        }
+
+        @Override
+        public boolean isOpen() {
+            return true;
+        }
+
+        @Override
+        public void close() {
+            throw new UnsupportedOperationException();
+        }
+    }
 }